In conventional manual wind cameras, the exposed filmstrip is rewound into the confines of a lighttight film cartridge before a cartridge chamber door is opened to release the cartridge for processing.
With the advent of the so-called Advanced Photographic System (APS), a portion of an exposed filmstrip can be rewound back into the confines of the film cartridge and the filmstrip can be subsequently readvanced to the next unexposed portion of the filmstrip to continue exposure at a later time.
In any event, the filmstrip must be rewound before the cartridge chamber door is opened. The thrusting cartridge has a status indicator on the cartridge which describes the current state of the film cartridge, either exposed, partially exposed, or not exposed, which is plainly visible to the user.
In order for the cartridge chamber door to be opened, the rotatable film spool of the film cartridge must be in a specific rotational alignment, hereinafter referred to as the parked position. If the spool is not in the parked position, the cartridge chamber door cannot be opened which may be an annoyance to a user of the camera, who may not fully understand the reasons why the cartridge chamber door fails to open. Though the status indicator of the film cartridge correctly relates this information, there is no effective way to relay the status information to the user.
One possible means of providing the information might be to make the door partially transparent to visually scan the state of the cartridge. Though this technique may be suitable for conventional 35 mm film cartridges, it is not suitable for thrusting type film cartridges, such as those described in U.S. Pat. No. 5,248,108, among others, which can only be made lighttight when the active light lock which is used to open and close the film door of the cartridge. If a transparent cover were used, ambient light would breach the lighttight integrity of the camera and prematurely fog the filmstrip.
Therefore, there is a need to provide a user with the film cartridge status to know when the film cartridge door of the camera can be opened, and why the door cannot be opened when the spool is not in the parked position.